Weiguo Zhu

MicroRNA-29a regulates pro-inflammatory cytokine secretion and scavenger receptor expression by targeting LPL in oxLDL-stimulated dendritic cells

There is increasing evidence that microRNAs (miRNAs) play important roles in cell proliferation, apoptosis and differentiation that accompany inflammatory responses. However, whether microRNAs are associated with DC immuno‐inflammatory responses with oxidized low density lipoprotein (oxLDL) stimulation is not yet known. Our study aims to explore the link of miRNAs with lipid‐overload and immuno‐inflammatory mechanism for atherosclerosis. In DCs transfected with microRNA‐29a mimics or inhibitors, we showed that microRNA‐29a plays an important role in proinflammatory cytokine secretion and scavenger receptor expression upon oxLDL‐treatment. Furthermore, we suggest an additional explanation for the mechanism of microRNA‐29a regulation of its functional target, lipoprotein lipase. We conclude that microRNA‐29a could regulate pro‐inflammatory cytokine secretion and scavenger receptor expression by targeting lipoprotein lipase in oxLDL‐stimulated dendritic cells.

MicroRNA‐146a regulates the maturation process and pro‐inflammatory cytokine secretion by targeting CD40L in oxLDL‐stimulated dendritic cells

There is increasing evidence that microRNAs (miRNAs) play important roles in cell proliferation, apoptosis and differentiation that accompany inflammatory responses. However, whether miRNAs are associated with dendritic cell (DC) immuno‐inflammatory responses to oxidized low density lipoprotein (oxLDL) stimulation is yet unknown. Our study aims to explore the link of miRNA to lipid‐overload and the immuno‐inflammatory mechanism for atherosclerosis. Human primary monocyte‐derived DCs were transfected with miR‐146a mimics and inhibitor, and then stimulated by oxLDL. For the flow cytometric analysis of the DC immunophenotype, supernatants were collected to determine inflammatory chemokine markers. Our study clearly revealed that miRNA‐146a regulates the maturation process and pro‐inflammatory cytokine secretion in DCs by targeting CD40L in ox‐LDL‐stimulated DCs.

Angiotensin-(1–7) enhances angiotensin II induced phosphorylation of ERK1/2 in mouse bone marrow-derived dendritic cells

It is well known that angiotensin-(1-7) (Ang-(1-7)) counterbalances vasoconstrictive and proliferative functions of angiotensin II (Ang II), some of those actions are via inhibition of Ang II induced activation of mitogen-activated protein kinases(MAPK). This study investigated the effects of Ang-(1-7) on Ang II-mediated cell signaling pathways in mouse bone marrow-derived dendritic cells (DC). The expression of receptor Mas and angiotensin-converting enzyme-related carboxypeptidase (ACE2) mRNA was examined by reverse transcription-polymerase chain reaction (RT-PCR); activation of MAPK was detected by immunoblotting after incubation of dendritic cells with Ang II in the presence or absence of Ang-(1-7), valsartan, PD123319, and D-Ala(7)-Ang-(1-7). Ang II rapidly (5 min, 10(-7) mol/L) stimulated phosphorylation of extracellular signal-related kinase (ERK1/2); this effect was partially inhibited by Ang II type 1 (AT1) receptor antagonist valsartan and significantly attenuated by Ang II type 2 (AT2) receptor antagonist PD123319. Ang-(1-7) alone also induced phosphorylation of ERK1/2; co-treatment of Ang-(1-7) and Ang II markedly enhanced ERK1/2 phosphorylation, the enhancement was eliminated by the Ang-(1-7) receptor antagonist D-Ala(7)-Ang-(1-7). Both Ang-(1-7) and Ang II had no effect on p38 and c-Jun N-terminal kinase (JNK) phosphorylation. In conclusion, Ang II stimulates ERK1/2 phosphorylation via AT2 receptor in mouse DC, Ang-(1-7) enhances this effect. Generation of Ang-(1-7) by DC could thereby counteract on the pro-inflammatory function of locally generated Ang II.

Vascular oxidative stress increases dendritic cell adhesion and transmigration induced by homocysteine

Atherosclerosis is a long-term chronic inflammatory and immunological disease. Endothelial dysfunction and the dendritic cell (DC) immune response are pivotal early events in atherogenesis. This study investigated the effects and possible mechanisms of action of homocysteine (Hcy) on DC adhesion to and transmigration between endothelial cells (ECs), and indicated a novel immunoregulatory mechanism by which Hcy induces atherogenesis. When ECs were stimulated with increasing concentrations of Hcy, immunofluorescence showed that endothelial reactive oxygen species (ROS) generation strikingly increased, while nitrite assay showed that nitric oxide (NO) release markedly decreased. Furthermore, DC adhesion and transmigration were significantly increased when ECs were activated by Hcy. However, pretreatment of ECs with antioxidant before Hcy markedly attenuated the induction of DC adhesion and transmigration, dependent on the intracellular ROS decrease and endothelial NO increase. In conclusion, DC adhesion and transmigration are significantly increased by vascular oxidative stress under conditions of elevated Hcy levels. These findings provide insight into the inflammatory processes and immune responses occurring in atherosclerosis induced by Hcy.

Impairment of Monocyte-derived Dendritic Cells in Idiopathic Pulmonary Arterial Hypertension

Background and AimWith the development of immunology, the role of immune inflammation in idiopathic pulmonary arterial hypertension (IPAH) has attracted interest. Recently, it was discovered that dendritic cells, which are key players in immune inflammation, are implicated in the pathogenesis of IPAH. To elucidate the role of dendritic cells in human IPAH, we compared the changes in the number and immunological function of monocyte-derived dendritic cells (MoDCs) from the peripheral blood of patients with IPAH and healthy controls.MethodsThe numbers of MoDC subsets (including plasmacytoid dendritic cells (pDCs) and myeloid dendritic cells (mDCs)) in circulating peripheral blood mononuclear cells (PBMCs) was analyzed by flow cytometry, and the concentrations of interleukin (IL)-12, IL-10, and tumor necrosis factor-alpha were measured by enzyme-linked immunosorbent serologic assay kits. The morphology, phenotypic expression, and the ability to stimulate T cell proliferation of MoDCs, cultured from PBMCs in vitro with granulocyte-macrophage colony-stimulating factor (GM-CSF) and IL-4, was analyzed by microscopy, flow cytometry, and MTT assay.ResultsThe results of the study are as follows: (1) The number of circulating mDCs was lower in IPAH patients than in controls (0.07 ± 0.01% to 0.14 ± 0.02%; p < 0.05). (2) IL-12 levels were higher in IPAH patients than in controls (p < 0.05). (3) MoDCs showed higher expression of CD1a (53.34 ± 7.43% to 19.29 ± 7.37%; p < 0.05), and lower expression of costimulatory molecule CD86 (64.54 ± 5.93% to 87.04 ± 4.82%; p < 0.05), and less ability to simulate T cell proliferation (when the ratio is 1:10) compared to the controls.ConclusionsThe study shows that it is possible to obtain typical DCs by culturing PBMCs from patients with IPAH with GM-CSF and IL-4, and it demonstrates that patients with IPAH have a significant change in the number of mDC and a marked immune deficiency of MoDCs.

Precise control of the number of walls formed during carbon nanotube growth using chemical vapor deposition.

We demonstrate a one-step approach for selecting the number of walls formed during carbon nanotube (CNT) growth by catalytic decomposition of CH(4) over Fe-Mo/MgO catalysts. Scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HRTEM), thermal gravimetric analysis (TGA) and Raman spectroscopy analyses indicate that high purity single-walled, double-walled and triple-walled carbon nanotubes can be synthesized by tuning the Fe:Mo atomic ratio of catalysts. The results reveal that the concentration of Mo in the catalyst plays an important role in the size of catalyst particles and in the deposition rate of carbon atoms during CNT growth. Thus, the wall numbers of CNTs can be controlled precisely.

Changes in proteomics profile during maturation of marrow‐derived dendritic cells treated with oxidized low‐density lipoprotein

Increasing evidence suggests that dendritic cells (DCs) and oxidized low‐density lipoprotein (ox‐LDL) participate in atherosclerosis. However, few data on the molecular mechanisms of this process are available. To address this question, we used iTRAQ labeling followed by LC‐MS/MS analysis to identify many proteins that changed markedly during the maturation of dendritic cells stimulated with ox‐LDL. Among a total of 781 identified proteins, 93 were upregulated and 100 were downregulated. The major and significant changes in upregulated proteins were that ox‐LDL not only affected the levels of intracellular cathepsins G, Z, D and S, but also significantly enhanced cathepsin S secretion by the treated cells. Our results may provide clues for a more comprehensive understanding the pathogenesis of atherosclerosis.

Ox-LDL can enhance the interaction of mice natural killer cells and dendritic cells via the CD48-2B4 pathway

The importance of the interaction between natural killer (NK) cells and dendritic cells (DCs) in the expansion of antiviral and antitumor immune responses is well documented; however, limited information on NK/DC interaction during atherosclerosis is available. Inflammation plays an important role in the development of atherosclerosis, and oxidized low-density lipoprotein (ox-LDL) is believed to play a critical role in the development and progression of atherosclerosis. In this study, we developed a NK/DC coculture system to examine the role of ox-LDL in modulating the interaction of mice NK cells and DCs. Fresh NK cells were cocultured with DCs in the absence or presence of ox-LDL. We examined the cytokines released during the interaction. This report provides the first evidence of an enhancement effect by ox-LDL on the NK/DC crosstalk. Notably, we found that ox-LDL significantly promoted the interaction of NK cells and DCs via CD48-2B4 contact-dependent mechanisms. These findings highlight the importance of NK/DCs crosstalk in atherosclerosis and provide new information about the possible mechanisms of atherosclerosis.

Distinct MAPK pathways are involved in IL-23 production in dendritic cells cocultured with NK cells in the absence or presence of angiotensin II.

Accumulated evidence suggests that the crosstalk between dendritic cells (DCs) and natural killer (NK) cells enhances each others capacity, and results in the production of a variety of soluble factors. However, little is known about the effect of DC-NK crosstalk in interleukin-23 (IL-23) production. In the present study we show that DC-NK coculture caused a high expression of IL-23, angiotensin II (Ang II) alone moderately increased IL-23 production in DCs, but decreased IL-23 secretion in the DC-NK coculture system. We found that Ang II does not influence DC maturation in DC-NK crosstalk. We next investigated the mitogen-activated protein kinase (MAPK) pathway in DCs. We found that Ang II increased IL-23 production through the extracellular signal-related kinase (ERK) pathway. All three MAPK members c-Jun N-terminal kinase (JNK), ERK and p38 were involved in IL-23 production in the DC-NK coculture system. In the presence of Ang II, only the JNK pathway seems to play a role in IL-23 production in DCs cocultured with NK. These data suggest that distinct MAPK pathways are involved in IL-23 production in DCs in response to different stimuli. This work demonstrates for the first time that IL-23 is produced in the DC-NK coculture system, and that Ang II is involved in DC-NK crosstalk. This data will act as a resource that allows further exploitation of role of immune response in atherosclerosis.

Expression of renin-angiotensin system on dendritic cells of patients with coronary artery disease.

Dendirtic cells (DCs) and renin–angiotensin system (RAS) have both been reported to contribute to the pathogenesis of atherosclerosis. Recently researches find the RAS expression on DCs and its effect on DCs’ differentiation and proinflammatory function. The pattern of RAS expression on DCs derived from normal monocytes vs that on DCs derived from cornoary artery diease was investigated. In 82 coronary artery disease (CAD) patients and healthy controls (CTL), expressions of angiotensin I-converting enzyme (ACE), angiotensin AT1 receptor and DC-specific ICAM-3-grabbing nonintegrin (DC-SIGN) on DCs were measured by western-blot: CAD patients had an increased expression of ACE, AT1 receptor and DC-SIGN compared to controls especially in acute myocardial infarction (AMI). Cardiovascular risk factors of cardiovascular disease and circulating anigotensin II (Ang II) were assessed and found increased in AMI compared with CTL. The DC-SIGN and high-sensitivity C-reactive protein (hsCRP) also had significant correlations with RAS expression on DCs. Our research demonstrated the RAS expressions on DCs and their increase in CAD especially AMI. The RAS activation on DCs may cause a series of changes such as enhancing recruitment of DCs, activating the T cells and increasing their proinflammtory functions. The recruitment and T cells contact ability of DCs increases through DC-SIGN may be one of pathogenesis of atherosclerosis and this function may promoted by tissue RAS. CRP may also have some effect to the local RAS exprssion on DCs.